Conventional micro-fluid ejection heads are designed and constructed with silicon chips having both ejection actuators (for ejection of fluids) and logic circuits (to control the ejection actuators). However, the silicon wafers used to make silicon chips are only available in round format. In particular, the basic manufacturing process for silicon wafers is based on a single seed crystal that is rotated in a high temp crucible to produce a circular boule that is processed into thin circular wafers for the semiconductor industry.
The circular wafer stock is very efficient for relatively small micro-fluid ejection head chips relative to the diameter of the wafer. However, such circular wafer stock is inherently inefficient for use in making large rectangular silicon chips such as chips having a dimension of 2.5 centimeters or greater. In fact the expected yield of silicon chips having a dimension of greater than 2.5 centimeters from a circular wafer is typically less than about 20 chips. Such a low chip yield per wafer makes the cost per chip prohibitively expensive.
Accordingly there is a need for improved structures and methods for making micro-fluid ejection heads, particularly ejection heads suitable for ejection devices having an ejection swath dimension of greater than about 2.5 centimeters.
In view of the foregoing and/or other needs, exemplary embodiments disclosed herein provide micro-fluid ejection heads and methods for making, for example, large array micro-fluid ejection heads. One such ejection head includes a substrate having a device surface with a plurality of fluid ejection actuator devices and a pocket disposed adjacent thereto. A chip associated with the plurality of fluid ejection actuator devices is attached in the pocket adjacent to the device surface of the substrate. A conductive material is adjacent to the device surface of the substrate and is in electrical communication with the chip.
Another exemplary embodiment disclosed herein provides a method for fabricating a micro-fluid ejection head. According to such a method, a chip is attached in a pocket adjacent to a device surface of a substrate and adjacent to a plurality of fluid ejection actuators that are adjacent to the device surface of the substrate. A blocking film is applied adjacent to the device surface of the substrate to span a gap between the chip and the device surface of the substrate. The gap is filled with a non-conductive material from a fluid supply surface of the substrate. The blocking film is removed and a conductive material is deposited adjacent to the device surface of the substrate and the filled gap for electrical connection to the chip.
Yet another exemplary embodiment disclosed herein provides another method for fabricating a micro-fluid ejection head. According to such a method, a chip is attached in a pocket adjacent to a device surface of a substrate and adjacent to a plurality of fluid ejection actuators that are adjacent to the device surface of the substrate. A conductive material is deposited adjacent to a device surface of the substrate. A support film is applied adjacent to the device surface of the substrate to span a gap between the chip and the device surface of the substrate. Another conductive material is deposited adjacent to the support film for electrical connection to the chip.
An advantage of the exemplary apparatus and methods described herein is that large array substrates, for example, may be fabricated from non-conventional substrate materials including, but not limited to, glass, ceramic, metal, and plastic materials. The term “large array” as used herein means that the substrate is a unitary substrate having a dimension in one direction of greater than about 2.5 centimeters. However, the apparatus and methods described herein may also be used for conventional size ejection head substrates.
Another advantage of exemplary embodiments disclosed herein is an ability to dramatically reduce the amount of semiconductor device area required to drive a plurality of fluid ejection actuators.